Internal emails uncovered by The Ferret reveal that the First Minister was advised to turn down a request for a meeting in 2018 so as not to become a “focus for criticism”. But officials said the public reason given for her refusal would be “on the standard basis of diary pressures”.

Campaigners reacted with sadness, saying that the Scottish Government’s “ears are closed”. The government stressed that it had “very limited scope” to address the issues raised.

Nuclear fuel was sent from an Australian research reactor to Dounreay on the north coast of Scotland for reprocessing in the 1990s. The resulting radioactive waste, amounting to 51 cemented drums, was originally due to be returned to Australia for disposal.

But under the terms of a waste substitution deal in 2014, Scottish and UK governments agreed that the drums should stay at Dounreay. Instead, the plan is to send four containers of “radiologically equivalent” waste to Australia from the Sellafield nuclear complex in Cumbria.

Two sites have been identified for a planned store for the waste in south Australia – Wallerberdina Station, near Hawker, and Kimber – both of which face opposition from indigenous communities. The Ferret reported in February that Scottish ministers had been advised that they had powers to prevent the waste being exported to protect human rights.